The present invention relates to a liquid-level detector and, more particularly, to an optoelectronic liquid-level detector.
An object of the present invention is to provide a liquid-level detector of high reliability.
Another object of the present invention is to provide a liquid-level detector of compact size and light weight.
Still another object of the present invention is to provide a liquid-level detector not having a mechanical portion.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a light-emitting element and a light-responsive element are mounted on a surface of a substrate. A U-shaped optical guide is disposed above the substrate in such a manner to optically connect the light-emitting element and the light-responsive element with each other. When the U-shaped optical guide is above the liquid-level, or, the U-shaped optical guide is positioned in air, the light-responsive element develops an output signal above a predetermined level. Contrarily, when the U-shaped optical guide is below the liquid-level, or, the U-shaped optical guide is dipped within liquid, the output level of the light-responsive element is below the predetermined value because the index of refraction of the material surrounding the U-shaped optical guide varies.